Production of potassium nitrate



Patented Dec. 8, 1931 FRIEDRICH mowam AND ERICH mun-ins, OF LUDWIGSHAFEN-Ofi-THE BHINEQ GEE MANY, ASSIG-NOR TO I. G. FARBENINDUSTRIE AKTIENGESELLS CHLAFT, 0F FRANK-w FORT-ON-THE-MAIN, GERMANY, A CORPORATION OF GERMANY PRODUCTION or rorassrumrmrna'rn N0 Drawing. Application filedAugust 19,1929, seriaitfo ;387, 79,,ai1aineerman mama-r 14, 1 ,928.

The present invention relates to the pro tions of calcium chloride containing nitrate are obtained, the working up of which is both difiicult and uneconomical. 7

We have now found that the yield of potassium nitrate can be considerably increased and in some cases can even be rendered quantitative, by carrying out the separation of the potassium nitrate in the presence of ammonia. For this purpose the ammonia can be added either before the conversion, for example by starting from an ammoniacal solution of one or of both the substances to be converted, or the ammonia can be added after mixin the components or after the conversion, for example, by passing gaseous ammonia into the reaction liquid. A saturation of the reaction liquid with ammonia is in many cases not necessary, for example, when converting equivalent quantities of calcium nitrate and potassium chloride at sufficiently low temperatures, for example 0 centrigrade,

a maximum yield of: potassium nitrate is obtained if from 20 to 25 parts of ammonia are employed for each 100 parts of water present.

The ammonia can be recovered from the residual ammoniacal solution in the .usual manner after the separation of the potassium nitrate.

The aforesaid process can be still further improved by cooling the mother liquor fromthe precipitated potassium nitrate to very low temperatures for example those between 0 and 30 below zero centigrade, and then treating it with gaseous ammonia or gases containing ammonia, for example, the gas mixtures obtained in the synthesis of am monia. Thereby, the calcium chloride is precipitated in the form of the double compound with ammonia CaCl fiNH The precipitate may be filtered ofi from the mother liquor containing nitrate, if necessary, with the employment of suction or pressure, andthe said it? liquor which is now freed from the greater part of the calciunr chloride may" either be ledback'jto the firstfstage of the process, namely for the conversionof freshamounts of calciuninitrate and potassiumchloride,

or may be directly workedup into potassium nitrate, for example, by concentration and crystallization. By-heating the double com. pound ofcalcium c hlorideand' ammonia, calcium chloride and pure ammonia are obtained. When employing this method of working it is not necessary to provide for the potassium. nitrate being precipitated as quantitatively as :possible in the conversion,

ing the remainder of the salt by the removal of the calcium chloride into a liquor whic'h canbe readily worked upor which is valuablefor arepeated operation. In the case described, for exa1nple,a yield ofabou t'95 per cent of precipitated potassium nitrate is.

quite sufiicient, and this can be obtained without difficulty.- 'It is necessary for the. formation OftheCaChfiNI-L that the partial K pressure of the ammoniashould be at'least '2 atmospheres.

Emample 1 64 kilograms of potassium chloride are introduced at centigrade into 100 litres of a solution containing 48 per cent by weight since it' is'easy toconvert the liquor containof calcium nitrate. After cooling to 0 cen of the water present contain about 5 parts of ammonia, whereby further quantities of potassium nitrate separate out. Altogether 85.5 kilograms of potassium n1- trate with a chlorine content of 3.3 per cent nitrogen and of 99.5

are obtained. This'corresponds to a yield of 96 per cent calculated with reference to referenceitopotassium., V c "Example 2 it; j

lution of 48 per cent strength. After cooling to 0"IG., wherebyp'art of' the potassium i nitrate is precipitated, gaseous ammonia is 1 passedinto the liquid until "it contains about 5 parts ofammonia for each 10 parts of water." Theprecipitated potassium nitrate v(1 91.9 parts) isfil'tered ofii', the remaining solution is saturated with ammonia .at0 C. and under a'pressure of ,5 ja'tmospheres. 202.6 parts of calciumichloride ammonia double compound CaCLfiNH are precipitated and filtered ofi. Therem'ainingsolution is used for" conversion of further amounts of 'calcium nitrate and potassium chloride.

l 1'. The process of producing potassium nitrate, which comprises converting calcium nitrate-with potassium chloride and separating thelpotassium nitrate in the presence of ammonia; c

2. The process of producingvpotassium nitrate, which comprises converting calcium nitrate with potassium -chloride and simul-. taneously separating the potassium nitrate in the presence of ammonia.

I 3. The process of producing potassium ni-j trate which'comprises converting calcium nitrate with potassium chloride, separating the potassium nitrate in the presence of'ammonia,

and treatingthe mother liquor with ammonia at a-temperature below 0 centigrade, thereby separating calcium chloridefin the form of its double compound with ammonia.

our hands. j

. FRIEDRICH FROWEIN.

ERICH RAIILFS.

P cent calculated with parts of potassium chloride are intro duced into 342 parts of calcium nitrate so- I n testimonywhereof'we have hereunto set 

